Since organic electroluminescent elements (which may hereinafter also be referred to as “elements” or “organic EL elements”) are capable of high-luminance light emitting using low voltage driving, they have been actively researched and developed. The organic electroluminescent elements have an organic layer between a pair of electrodes, and utilize, for light emitting, energy of the exciton generated as a result of recombination of the electron injected from a cathode and the hole injected from an anode in the organic layer. Since the organic electroluminescent elements can be provided as an element having diverse light emitting wavelengths, and have a high response speed and are relatively thin and light-weight, it is expected that they can be employed in a wide range of applications. Above all, it is important to develop the development of an organic electroluminescent element having high color purity and luminous efficiency is important in applications with full-color displays and the like, and the results of studies on various research and development have been reported.
PTL 1 describes that it is possible to attain light emission and a longer service life in the blue region in an element using a material in which a ring is formed with a single bond and a methylene chain with respect to a fused ring structure such as pyrene as a fluorescent material. In Examples of this literature, 3 kinds of compounds are used as a blue dopant, which has a chromaticity of about (0.14 or 0.16) and a maximum efficiency of about 7.8 cd/A, described in Table 6.
Furthermore, the literature 2, which is well-known, describes that an element having high efficiency and a wide gap (that is, considered to allow blue light emission to be performed) is obtained by using a molecule formed by subjecting benzofluorene to ring fusion and expansion as a light emitting material. In Examples of this literature, the spectrum of the element thus fabricated is disclosed, in which the wavelength is in a long and broad wave form and the maximum light emitting wavelength was about 462 nm on average.
In addition, PTLs 3 and 4 disclose a material in which two indole rings are fused symmetrically at 1-, 2-, 6-, and 7-positions of a pyrene ring, but according to the investigation of the present inventors, they have found that there are problems, for example, that the materials have an insufficient blue color purity and a change in the chromaticity due to deterioration by driving with a lowered luminous intensity (hereinafter also referred to as a change in the driving chromaticity), and have an increase in the voltage by driving (hereinafter also referred to as an increase in the driving voltage).